Over subsequent months, Hubble examined other spiral nebulae as he searched for more Cepheids with which to measure distances. Word of Hubble's observations was spreading among astronomers.

Galaxies shine in a rainbow of emissions from gas, dust, and stars. Each of these building blocks emits light at specific ...

A third category – nebulae with spiral structure – particularly intrigued astronomers. The Andromeda nebula, M31, was a prominent example. It’s visible to the naked eye from a dark site.

SEASON OF THE HARVEST MOON The Spiral Nebulae About Andromeda -- Movements and Occultations of the Planets. Share full article. Sept. 2, 1900. ...

Hubble worked hard, taking images of spiral nebulae every clear night and looking for the telltale variations of Cepheid variables. By the end of 1924, he had found 12 Cepheids in M31.

When he ran the numbers, he found that the spiral nebulae were far outside the Milky Way. He calculated that Andromeda was about 860,000 light-years away.

By 1922, he had topped off his survey with a further 17 spiral nebulae, all of which were receding — the fastest at an unprecedented 1,120 miles (1,800 km) per second.

The galactic masterpiece combines over 100 exposures to reveal previously unseen features of stars in formation.

Putting Isaac Roberts’ astonishing 1888 photographs of the Great Nebula in Andromeda and other spiral nebulae to cosmic effect at his argument’s outset, Pettigrew then immersed the reader in a ...

The headline read: Finds Spiral Nebulae are Stellar Systems: "Dr. Hubbell Confirms View That They Are 'Island Universes'; Similar to Our Own." On Sunday November 23, 1924, ...